Computer Replaced on Atlantis; NASA Targets Tuesday Launch

KENNEDY SPACE CENTER, Fla. — Technicians on Friday replaced a defective computer in the space shuttle Atlantis as they worked toward a Tuesday launch to deploy the Jupiter-bound Galileo probe.

Testing of the new $6-million unit began immediately and was to be completed today.

"All the work is going well at the launch pad," NASA spokeswoman Lisa Malone said. "We can launch on Tuesday if the testing goes without a hitch."

Shuttle managers planned to meet today to assess test results and decide when the interrupted countdown should be resumed. The countdown, which features nearly 18-hours of built-in "hold" time, could resume at midnight Sunday at the T-minus 19-hour mark.

A long-range weather forecast said conditions on Tuesday will be 70% favorable. It said a cold front was expected to move into Florida on Wednesday and "it appears weather would not be acceptable" on that day.

The task of replacing the 230-pound computer began soon after the countdown was halted Tuesday because the device gave a false pressure reading. Launch had been set for Thursday.

The tedious work involved removing engine heat shields, erecting access platforms and unhooking about two dozen connections between the computer and the shuttle. Because of limited space in the engine compartment, only six people could work there at a time.

Liftoff on Tuesday is tentatively scheduled for 9:57 a.m. PDT, the start of a 24-minute period in which Jupiter will be in the proper position to nearly cross paths with the Galileo spacecraft in 1995.